Dave Rogers
Bandaged ice that stampedes inexpensively through
You said that the steel temp would rise even after the fire has moved on.
If you think conduction would raise the temperature of the steel that was heated after the fire source has been exhuasted, you are hallucinating or you live in a parallel universe, in which basic principles of science are reversed.
I see you've done lots of thermal modelling to have drawn so confident a conclusion.
Heat propagates outward from a source. Its rate of propagation depends on the thermal conductivity of the material it propagates through. If a fire heats up a material of relatively low thermal conductivity but high thermal mass, then a localised heat reservoir is created. Heat will propagate outwards from this reservoir even when the heat source is removed, and nearby materials of higher thermal conductivity - for example, a steel support beam under a concrete floor - will therefore experience an increase in temperature even after the removal of the heat source.
Understanding this sort of thing is extremely difficult, and requires detailed analysis of the heat source and the structure around it. Computer simulations have, in recent years, made it at least possible, but it's still extremely complex and requires a great deal of computing power for a structure of significant size and complexity. Fortunately, NIST has done some modelling, and reported its results in detail. Some of their findings may appear counter-intuitive, but this is not particularly surprising given the complexity of the situation.
But it's important not to take too much notice of the ignorant and uneducated, who frequently confuse a counter-intuitive situation that follows inevitably from the laws of science with one in which the basic principles of science are reversed. The commonest cause for this is that they don't actually know what any of the basic principles of science actually are.
Dave